A Novel Elbow Pneumatic Muscle Actuator for Exoskeleton Arm in Post-Stroke Rehabilitation

Rehabilitation interventions play a vital role especially in most post-stroke care. Many rehabilitation robotic devices have been designed and developed to assist many individuals suffering from stroke or similar disabling illness and living with reduced mobility of the arms, hands and other joint. However, these devices remain unmanageable to use by the patients alone not only because they are cumbersome to use but also due to their weights, fix and non-portable characteristics, and so on. Here for elbow joint rehabilitation, we investigate and propose a novel exoskeleton soft robotic arm, which is wearable, lightweight and portable so that it would allow patients to perform repetitive motion therapy more often with a greater intensity in their homes and relevant to their daily activities. The proposed arm consists of various novel pneumatic Muscle Actuators (pMA) capable of bending in contrary to traditional pMA. Analysis, design, integration and characterisation of the proposed arm are presented and geometrical and numerical models are obtained. Various experiments revealed its behaviour and the relationship among pressure, length, force, and bending angle in different setups such as isotonic and isometric. The nonlinear, time varying and intractable dynamic of the constructed prototype demanded the design and development of an appropriate closed loop controller for adhering to target rehabilitation profiles. As proof of the concept a Model Reference Adaptive Control (MRAC) was designed and results were presented. By achieving design objectives, this study shows that the proposed portable exoskeleton has the ability to offer more effective intense rehabilitation therapies at home without the need to therapists and with a lower cost.